Transmission Fluid Change Theory

[Mavster Mechanic]

P.s. I have a hybrid and will go long intervals on mine.

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[Maverick Country Club]

To expand this is just a different way to state Peano's axioms. The doggie treat is the natural number, I am the successor function and the dog is treat counter. The fundamental rule of addition. Give me a treat feed the dog, the addition is how many treats did I feed the dog not how I feed the dog. All your grade school math is based on this and the rules that logically fall out of this.

Unless the dog dies or it finds food elsewhere it will keep coming back for another treat one at a time for potentially an infinite amount of times. That is how you prove all those rules aka induction.

Math is a logic based exercise not a language like taught in grade school. That is just one way of applying it, it is not the it. That they don't show kids this in grade school these days to my knowledge at least once before graduating should be criminal

Now that’s what I’m talking about!!! … So can the condition of a mixture of working fluid of various states of wear be calculated for real world applications?

 

[Maverick Country Club]

Partial drains and partial refills will dilute dirt & contaminates.

Partial drains and partial refills will add in some new additives.

But the old half stays old and only gets older.

The question that has not been answered is: what happens to
The old; older; eventually really old fraction that remains the second and third.... times you do this?

Weird example: if oil changes to vinegar; would you want to dilute it by half or take it all out (or as much as possible)?

Since you like thought experiments lets go a step further.

What if oil changes to vinegar (acetic acid) at 30k but does little harm. But if left in there until 40k further decomposes into hydrochloric acid and does great harm.

Would you want to leave any fraction of the old in there each time?

Not saying this is how it works.
Just a thought experiment for you.

Great!!! I’m confident I understand this.

Anyone would want all the fluid removed.

Thats just it though, we have no choice with the transmission fluid because you can’t drain all the fluid, only half because the other half is trapped in the torque converter unless you trust the flushing process or you split the transmission. Really enjoying the dialog.

 

[Mavster Mechanic]

@Maverick Country Club

Aren't you the one who wanted to skip flushing? Or did I confuse you with the guy in post #1?

 

[Mavster Mechanic]

P.S. I think you could routinely do the partial drains and partial fills.

I just think it's not quite the same thing, else that would be the SOP.

Knowwhatimean?

 

[Maverick Country Club]

@Maverick Country Club

Aren't you the one who wanted to skip flushing? Or did I confuse you with the guy in post #1?

Ok David,

 

[Maverick2022XL]

Now that’s what I’m talking about!!! … So can the condition of a mixture of working fluid of various states of wear be calculated for real world applications?

Short answer maybe.

You need to ask the right question which is: Is motor oil a Newtonian fluid? That is a trick question.

More importantly what is a Newtonian fluid? Simply it is any fluids that have a linear relation between force applied on it and flow rate. Conversely non-Newtonian fluids are non-linear.

The answer is motor oil is both depending on it's shear rate.

So maybe.

 

[Maverick Country Club]

Short answer maybe.

You need to ask the right question which is: Is motor oil a Newtonian fluid? That is a trick question.

More importantly what is a Newtonian fluid? Simply it is any fluids that have a linear relation between force applied on it and flow rate. Conversely non-Newtonian fluids are non-linear.

The answer is motor oil is both depending on it's shear rate.

So maybe.

 

[Maverick2022XL]

You missed the trick, I said motor oil not transmission. The key point is both have viscosities. so the next question is: Does viscosity of transmission oil degrade over time at the shear rate you want to measure it at aka operating temperature?

 

[Maverick2022XL]

Horse here is some water....
https://www.atlanticlubes.com/blog/...acteristics-of-automatic-transmission-fluids/

In your case you probably want to do the Brookfield method mentioned there since it should be easier to do without lab equipment.

 

[Maverick Country Club]

Microstructures
A shear flow causes rearrangement of the microstructure of non-Newtonian fluids. Changes in the molecular or particle structure of the fluids can constitute part of this reorganizing.

 

[sajohnson]

Isn't it great that all of the world's other problems have been solved?

The OP's method sounds good to me. In fact, most transmission fluid changes have been done that way for decades.

The only way to remove all of the old ATF is with a flush. My understanding is that a flush is generally safe for lower mileage transmissions that have been well maintained, but they can cause problems with older transmissions.

The drain and fill method is still routinely used and less likely to cause issues.

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